The purpose of the work described in this proposal is to continue to study the mechanisms of cellular immunity and hypersensitivity. Our aim is to acquire knowledge of the basic mechanisms that involve sensitized lymphocytes, the mediators they produce and the macrophages that are recruited and activated, which can be used to rationally manipulate these cellular processes. Information gained would be applicable to human clinical conditions where enhancement of cellullar immunity might lead to prevention or alleviation of disease, such as infections or neoplasia, or where suppression might diminish injury to tissue caused by cellular hypersensitivity. In this proposal, we plan further studies on a macrophage receptor for migration inhibitory factor (MIF), produce antibodies to guinea pig pH3-MIF which has been purified to apparen homogeneity, continue studies on the purification and characterization of human MIF and macrophage activating factor (MAF), further study on the activation of human macrophages by MAF includingthe delineation of subsets of human monocyte/ macrophages by surface markers, and determine whether type II collagen-induced autoimmune polyarthritis in rats can be suppressed by immunological means.